1
Scanners for Security Screening
and for Theft and Contraband
Detection
By
Dr. Shengli Niu
Senior Specialist on Occupational Health
SafeWork/ILO
Personal Scanners
Figure 1 Backscatter Systems and
Sample Images
(NCRP Commentary No. 16)
RapiscanRapiscan’’ss Secure 1000Secure 1000™™ A S & E A S & E BodySearchBodySearch™™
Mobile unit of the type allegedly used for security purposes in
Tampa, Florida, USA, to image the inside of cars and trucks
accessing the 2009 Super Bowl venue
Personal & Cargo Scanners
•There are a number of cargo systems in use for the inspection of trucks, sea
containers and rail cars.
•They consist of radionuclide devices or radiation generators. The radionuclide
type use either Cs-137 or Co-60 sources.
•X-ray generators, operating at the 100’s kVp range (up to 450 kVp), have been
replaced by high-energy linear accelerators (from 6 to 15 MeV), that can
penetrate several inches of steel and image the contents within any cargo
container.
•CT scanners for cargo screening are under development.
•Neutron generators are also used for cargo scanning.
•Neutrons have the required penetration, they interact with matter in a manner
complementary to X-rays and they can be used to determine elemental
composition.
Dosimetry
Type MF* HV
(kV)
Current
(mA)
Hp(10)
(µSv)
H*(10)
(µSv)
Cargo (B,T) A 450 6.65 0.4
0.2
0.4 slow
0.2 fast
Person (T) B 160 3.7 5.5 / 5 4 / 4.2
Person (T) C 140 0.65 5 / 6 4-13 / 5.7
Person (T) C 140 0.18 2 1.5
Person (T) C 220 1.0 3 / 3.6 2 / 3.2
Person (B) D 50 5.0 0.03 0.04 / 0.07
Summary of the maximum mean dose values for
different types of scanners
Dosimetry
Effective doses per scan from two backscatter systems
(NCRP)
Effective Dose 50 kVp 125 kVp
Anterior View 0.03 µSv 0.03 µSv
Posterior View 0.01 µSv 0.02 µSv
Operator dose and Bystander
dose
(outside primary beam)
Indistinguishable from background
Standards and Guidelines
• The first NCRP report on human imaging for security purposes,
published in 2003 as Commentary 16, clearly stated that
transmission scanners were not supposed to be used as a routine
screening tool.
• The report recognized that they were being used in countries
outside the United States for workers exiting mines and in some
“foreign” airports in lieu of body searches.
• Their recommendation was that no member of the public should
receive more than 0.25 mSv per year and that scanner operators
were to have the same limitation.
• For backscatter systems, “an effective dose of 0.1 µSv per scan
would allow 2,500 scans of an individual annually”.
• For transmission systems, “at 10 µSv per scan, an effective dose
of 0.25 mSv would be reached after 25 scans”
Standards and Guidelines
• The report on cargo scanners establishes 5 mSv as the dose limit
for individuals within the cargo container, but goes on to say that
“acute doses up to 50 mSv are allowable for radiation workers
who may need to receive this dose as part of a specific work
assignment and the small increase in cancer risk is not
considered particularly hazardous”, de facto allowing that value as
the occupational dose limit.
• Cargo scanners have been installed in airports and seaports. In
the United States, all cargo that is loaded aboard passenger
planes will have to be screened (by 2010).
Standards and Guidelines
• The International Electrotechnical Commission (IEC)is currently in
the process of developing two international standards, one on
personal scanners and another one on cargo scanners.
• The first one specifies general characteristics, general test
procedures, radiation characteristics, electrical characteristics,
environmental influences, mechanical characteristics, safety
requirements and provides examples of acceptable methods in
terms of dose to the whole or part of the body and the time taken
for each screening procedure.
Regulatory Control Concerns
Who has the authority in each country to enforce the ionizing radiation
safety aspects?
• Rediation Protection
• Public Health
• Home security
• Custom
• Others
Regulatory Control Concerns
•The UK has also justified the use of X/gamma radiation scanners by the
Immigration Services for detecting people seeking to enter the UK illegally in
vehicles and/or freight, by clandestine means.
•The United States has not established any formal mechanism for the
manufacture and use of theses devices, but, in July 2008, the Interagency
Steering Committee on Radiation Standards published “Guidance for Security
Screening of Humans Utilizing Ionization Radiation”, a document intended to
assist US federal agencies to elaborate technical criteria for the justification of
the screening practice and establish a radiation safety program.
• For the justification process, the following steps should be taken: “Define the
need, evaluate options, evaluate privacy concerns, assess radiation risks from
the technology and the net benefit of implementation, evaluate agency’s ability
to implement the practice and reach a concluding decision”.
Regulatory Control Concerns
For the justification process, “the following elements of the decision process
should have been appropriately considered and documented:
1) The security need should be defined including the magnitude of the threat
and the risk of not implementing the chosen security practice.
2) The various options should have been considered, including their
effectiveness and their limitations.
Regulatory Control Concerns
3) Technologies should have been evaluated based on the expected reduction
of the security threat as weighed against the risks associated with the
screening technology and social or legal implications. (Risks evaluated should
include electrical shock, physical hazards, radiation exposures, environmental
factors and any other associated risks).
4) The agency should have confirmed the availability of sufficient resources
and its ability to implement the chosen security screening method. The
decision should include an initial plan for instituting the necessary programs
and allocating resources.
5) There should be a documented commitment for periodic reassessment of
the justification and optimization processes for the practice chosen and for
ongoing conformity assessment of the systems adopted”.
Current use of personal
and cargo scanners
•Personal scanners have been mainly installed at airports. Some examples
are: Heathrow in the UK; Schiphol in The Netherlands, and in the US:
Phoenix, Arizona; JFK, New York; Los Angeles, California, and Dallas Fort
Worth, Texas. Anecdotal evidence by travelers who have undergone the
procedure suggest that the operators are either unfamiliar with or cannot
convey to the public the operation of the system or its radiation risks.
•Cargo scanners have been installed in airports and seaports. In the United
States, all cargo that is loaded aboard passenger planes will have to be
screened by 2010. Vehicle scanners have been deployed at public places. A
mobile gamma ray inspection system has been designed to “non-intrusively
inspect the contents of trucks, containers and cargo for purposes of manifest
verification, contraband interception, and explosives, weapons or threat
identification” .
Justification of the use of scanners.
proper maintenance and calibration.
Impact of world-wide use, especially if for personal screening,
transmission rather than backscatter scanners are used as the
dose per scan is 100 times higher.
Main concerns
Requirement 10: Justification of practices
The government or the regulatory body shall ensure that only
justified practices are authorized.
3.16 The government or the regulatory body, as appropriate, shall ensure that
provision is made for the justification of any type of practice and for review of the
justification, as necessary, and shall ensure that only justified practices are
authorized.
Revision of the International Basic Safety Standards
for Protection against Ionizing Radiation and for the
Safety of Radiation Sources
http://www-ns.iaea.org/committees/files/CSScomments/1038/DS379-Draft5.0-21Mar2011.doc
3.17 The following practices are deemed to be not justified:
(a) Practices, except for justified practices involving medical exposure,
that result in an increase in activity, by the deliberate addition of radioactive
substances or by activation, in food, feed, beverages, cosmetics or any other
commodity or product intended for ingestion, inhalation or percutaneous intake
by, or application to, a person;
(b) Practices involving the frivolous use of radiation or radioactive
substances in commodities or in products such as toys and personal jewellery or
adornments, which result in an increase in activity, by the deliberate addition of
radioactive substances or by activation;
(c) Human imaging using radiation used as a form of art or for publicity
purposes.
Revision of the International Basic Safety Standards
for Protection against Ionizing Radiation and for the
Safety of Radiation Sources
3.18 Human imaging using radiation that is performed for occupational,
legal or health insurance purposes, and is undertaken without
reference to clinical indication, shall normally be deemed to be not
justified. If, in exceptional circumstances, the government or the
regulatory body decides that the justification of such human imaging for
specific practices is to be considered, the requirements of paras 3.61–
3.64 and 3.66 shall apply.
3.19 Human imaging using radiation for theft detection purposes shall
be deemed to be not justified.
Revision of the International Basic Safety Standards
for Protection against Ionizing Radiation and for the
Safety of Radiation Sources
3.20 Human imaging using radiation for the detection of concealed
objects for anti-smuggling purposes shall normally be deemed to be not
justified. If, in exceptional circumstances, the government or the
regulatory body decides that the justification of such human imaging is
to be considered, the requirements of paras 3.61–3.67 shall apply.
3.21 Human imaging using radiation for the detection of concealed
objects that can be used for terrorism or to pose a national security
threat shall be justified only by the government. If the government
decides that the justification of such human imaging is to be
considered, the requirements of paras. 3.61–3.67 shall apply.
Revision of the International Basic Safety Standards
for Protection against Ionizing Radiation and for the
Safety of Radiation Sources
Requirement 18: Human imaging using radiation for purposes other
than medical diagnosis, medical treatment or biomedical research
The government shall ensure that the use of ionizing radiation for
human imaging for purposes other than medical diagnosis, medical
treatment or biomedical research is subject to the system of protection
and safety.
Revision of the International Basic Safety Standards
for Protection against Ionizing Radiation and for the
Safety of Radiation Sources
3.61 The government, if so decided in accordance with paras 3.18, 3.20 and
3.21, shall ensure that the requirements of para. 3.16 for the justification of
practices are applied to any type of human imaging procedure in which radiation
is used for purposes other than for medical diagnosis or medical treatment or as
part of a programme of biomedical research. The justification process shall
include the consideration of:,
(a)The benefits and detriments of implementing the type of human imaging procedure;
(b)The benefits and detriments of not implementing the type of human imaging procedure;
(c)Any legal or ethical issues associated with the introduction of the type of human imaging
procedure;
(d)The effectiveness and suitability of the type of human imaging procedure, including the
appropriateness of the radiation equipment for the intended use;
(e)The availability of sufficient resources to conduct the human imaging procedure safely
throughout the intended period of the practice.
Revision of the International Basic Safety Standards
for Protection against Ionizing Radiation and for the
Safety of Radiation Sources
3.62 If it has been determined through the process specified in para. 3.61 that a
particular practice of human imaging using radiation is justified, then, such a
practice shall be subject to regulatory control.
3.63 The regulatory body, in cooperation with other relevant authorities,
agencies and professional bodies, as appropriate, shall establish the
requirements for regulatory control of the practice, and for review of the
justification.
Revision of the International Basic Safety Standards
for Protection against Ionizing Radiation and for the
Safety of Radiation Sources
3.64 For human imaging using radiation conducted by medical personnel using medical radiological
equipment, which exposes humans to radiation for employment related, legal or health insurance purposes
without reference to clinical indications:
(a) The government shall ensure, on the basis of consultation between relevant authorities,
professional bodies and the regulatory body, that dose constraints are established for such human imaging;
(b) The registrant or licensee shall ensure that the appropriate optimization requirements for
medical exposure in paras 3.161–3.176 are applied, with dose constraints as required in (a) above used
instead of diagnostic reference levels.
Such purposes include assessment of fitness for employment (prior to employment or periodically during
employment), assessment of physiological suitability for a career or a sport, assessment of athletes before
a selection or transfer, determination of age for legal purposes, obtaining of evidence for legal purposes,
detection of drugs concealed within the body, immigration or emigration requirements, pre-insurance
checks and obtaining evidence for the purposes of a compensation claim.
Revision of the International Basic Safety Standards
for Protection against Ionizing Radiation and for the
Safety of Radiation Sources
3.65 Procedures with inspection imaging devices in which radiation is used to expose
persons for the purpose of detection of concealed weapons, contraband or other objects on
or within the body shall be considered to give rise to public exposure. Registrants and
licensees shall apply the requirements for public exposure in planned exposure situations.
In particular, registrants and licensees shall ensure that optimization of protection and safety
is subject to any dose constraints for public exposure set by the government or the
regulatory body.
3.66 Registrants and licensees shall ensure that all persons who are to undergo procedures
with inspection imaging devices in which ionizing radiation is used are informed of the
possibility of requesting the use of an alternative inspection technique that does not use
ionizing radiation, where available.
3.67 The registrant or licensee shall ensure that any inspection imaging device used for the
detection of concealed objects on or within the body, whether it is manufactured in or
imported into the State in which it is used, conforms to applicable standards of the
International Electrotechnical Commission or the International Organization for
Standardization or to equivalent national standards.
Revision of the International Basic Safety Standards
for Protection against Ionizing Radiation and for the
Safety of Radiation Sources